/* 01 · 设计令牌与基础层 */
:root {
  color-scheme: light;
  --bg: #f6f4ef;
  --surface: #fffaf0;
  --text: #292820;
  --muted: #696356;
  --accent: #80602d;
  --border: #d8cfbd;

  --reader-size: 20px;
  --reader-leading: 1.8;
  --font-serif: "Songti SC", "STSong", "SimSun", serif;
  --font-sans: system-ui, -apple-system, "Segoe UI", "PingFang SC",
    "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, "SFMono-Regular", Consolas, "Liberation Mono",
    monospace;
  --reader-font: var(--font-serif);
  --terminal-bg: #0a0e27;
  --terminal-text: #9cc2ff;

  --radius: 12px;
  --figure-radius: 8px;
  --shadow: 0 12px 40px #0003;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 48px;
  --space-8: 64px;

  --site-width: 1120px;
  --reader-width: 38em;
  --site-gutter: 40px;
  --grid-gap: 24px;
  --topbar-height: 56px;
  --bottombar-height: 48px;
  --touch-target: 44px;
  --motion-duration: 160ms;
}

html[data-theme] {
  color-scheme: light;
}

html[data-theme="light"] {
  --bg: #ffffff;
  --surface: #f5f7f8;
  --text: #20262c;
  --muted: #58616b;
  --accent: #365f78;
  --border: #d7dde2;
}

html[data-theme="dark"] {
  color-scheme: dark;
  --bg: #171c22;
  --surface: #222a33;
  --text: #e3e8ed;
  --muted: #adb9c6;
  --accent: #e1bd79;
  --border: #46515e;
}

html[data-theme="night"] {
  color-scheme: dark;
  --bg: #191610;
  --surface: #242016;
  --text: #ded0b2;
  --muted: #b2a487;
  --accent: #d2ae70;
  --border: #514634;
}

html[data-font="sans"] {
  --reader-font: var(--font-sans);
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme]) {
    color-scheme: dark;
    --bg: #171c22;
    --surface: #222a33;
    --text: #e3e8ed;
    --muted: #adb9c6;
    --accent: #e1bd79;
    --border: #46515e;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  background: var(--bg);
  font-size: 100%;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-padding-block-start: var(--space-5);
}

body {
  min-width: 0;
  min-height: 100vh;
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.5;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  margin: 0 0 var(--space-4);
  color: var(--text);
  font-weight: 650;
  line-height: 1.25;
  overflow-wrap: break-word;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

p,
ul,
ol,
dl,
blockquote,
figure {
  margin: 0 0 var(--space-4);
}

ul,
ol {
  padding-inline-start: 1.75em;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
}

a:hover {
  text-decoration-thickness: 2px;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
  border: 0;
}

hr {
  height: 0;
  margin: var(--space-6) 0;
  border: 0;
  border-block-start: 1px solid var(--border);
}

button,
input,
select,
textarea {
  font: inherit;
}

button,
select,
textarea,
input:not([type="range"]):not([type="checkbox"]):not([type="radio"]) {
  color: inherit;
}

button {
  cursor: pointer;
}

button:disabled,
input:disabled,
select:disabled,
textarea:disabled {
  cursor: not-allowed;
}

code,
kbd,
samp,
pre {
  font-family: var(--font-mono);
}

::selection {
  background: var(--accent);
  color: var(--bg);
}

:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}

.site-shell,
.site-container {
  width: 100%;
  max-width: var(--site-width);
  margin-inline: auto;
  padding-inline: var(--site-gutter);
}

.site-shell .site-container {
  padding-inline: 0;
}

.site-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4) var(--space-5);
  min-height: var(--topbar-height);
  padding-block: var(--space-4);
  border-block-end: 1px solid var(--border);
}

.site-footer {
  margin-block-start: var(--space-8);
  padding-block: var(--space-5) var(--space-6);
  border-block-start: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.875rem;
  overflow-wrap: anywhere;
}

.skip-link {
  position: fixed;
  z-index: 1000;
  inset-block-start: var(--space-3);
  inset-inline-start: var(--space-3);
  max-width: calc(100% - 24px);
  min-height: var(--touch-target);
  padding: var(--space-3) var(--space-4);
  transform: translateY(calc(-100% - 24px));
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--accent);
  font-weight: 600;
}

.skip-link:focus {
  transform: translateY(0);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  clip-path: inset(50%);
  border: 0;
  white-space: nowrap;
}

html:not([data-js]) .js-only {
  display: none;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-width: var(--touch-target);
  min-height: var(--touch-target);
  padding: var(--space-3) var(--space-5);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  font: inherit;
  font-weight: 600;
  line-height: 1.5;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  transition: border-color var(--motion-duration) ease;
}

.button:hover {
  border-color: var(--accent);
  text-decoration: none;
}

.button-primary {
  border-color: var(--accent);
  background: var(--accent);
  color: var(--bg);
}

.button-secondary {
  background: transparent;
  color: var(--accent);
}

.button:disabled,
.button[aria-disabled="true"] {
  opacity: 0.55;
  cursor: not-allowed;
}

.text-link {
  color: var(--accent);
  text-decoration-line: underline;
  text-underline-offset: 0.25em;
  overflow-wrap: anywhere;
}

.card {
  min-width: 0;
  padding: var(--space-5);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}

.eyebrow {
  margin: 0 0 var(--space-3);
  color: var(--muted);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.12em;
}

.section-heading {
  margin-block: 0 var(--space-5);
  font-size: 1.5rem;
}

@media (max-width: 767px) {
  :root {
    --site-gutter: 20px;
    --grid-gap: 16px;
  }
  body { font-size: 14px; }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none;
    transition: none;
    scroll-behavior: auto;
  }
}
/* 02 · 主页与目录 */
.home-main {
  max-width: 1120px;
  margin-inline: auto;
  padding: 48px 20px 64px;
}
.home-hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 32px;
  padding-block: 16px 48px;
}
.home-hero > * { min-width: 0; }
.hero-heading { align-self: center; }
.book-title {
  margin: 0;
  color: var(--text);
  font-family: var(--font-serif);
  font-size: 36px;
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: .08em;
}
.book-subtitle {
  margin: 16px 0 0;
  color: var(--accent);
  font-size: 16px;
  line-height: 1.5;
  letter-spacing: .06em;
}
.hero-introduction {
  align-self: center;
  color: var(--text);
  font-size: 16px;
  line-height: 1.8;
  overflow-wrap: anywhere;
}
.hero-introduction p { margin: 0 0 16px; }
.hero-introduction p:last-child { margin-bottom: 0; }
.book-facts {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.book-facts > * {
  flex: 1 1 120px;
  min-width: 0;
  margin: 0;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.book-facts dt {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.5;
}
.book-facts dd {
  margin: 8px 0 0;
  font-size: 24px;
  font-weight: 600;
  line-height: 1.25;
  font-variant-numeric: tabular-nums;
}
.book-facts strong {
  display: block;
  color: var(--accent);
  font-size: 24px;
  line-height: 1.5;
}
.reading-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
}
.reading-actions > a,
.toc-actions > a,
.back-to-top {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 8px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--accent);
  background: var(--surface);
  font-weight: 600;
  line-height: 1.5;
  text-align: center;
  text-decoration: none;
  overflow-wrap: anywhere;
}
#continue-reading {
  border-color: var(--accent);
  color: var(--accent);
}
#continue-reading[hidden] { display: none; }
.reading-actions > .toc-entry {
  border-color: transparent;
  background: transparent;
  text-decoration: underline;
  text-underline-offset: .25em;
}
.reading-features {
  padding-block: 32px;
  border-top: 1px solid var(--border);
}
.reading-features > h2,
.feedback-card > h2,
.license-section > h2 {
  margin: 0 0 24px;
  font-size: 24px;
  line-height: 1.25;
}
.feature-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
}
.feature-card {
  min-width: 0;
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.feature-card h3 {
  margin: 0 0 12px;
  color: var(--text);
  font-size: 18px;
  line-height: 1.5;
}
.feature-card p {
  margin: 0;
  color: var(--muted);
  line-height: 1.8;
}
.reading-note {
  margin: 24px 0 0;
  padding-inline-start: 16px;
  border-inline-start: 3px solid var(--accent);
  color: var(--muted);
  font-size: 14px;
  line-height: 1.8;
}
.feedback-card {
  margin-block: 32px;
  padding: 24px;
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  background: var(--surface);
}
.contact-list {
  display: grid;
  gap: 12px;
  margin: 16px 0 0;
  padding: 0;
  list-style: none;
}
.contact-item {
  min-width: 0;
  color: var(--muted);
  line-height: 1.8;
  overflow-wrap: anywhere;
}
.contact-item a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  max-width: 100%;
  color: var(--accent);
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: .25em;
  overflow-wrap: anywhere;
}
.license-section {
  padding-block: 32px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 14px;
  line-height: 1.8;
}
.license-section > h2 { font-size: 18px; }
.license-section p { margin: 0 0 12px; }
.back-to-top { margin-top: 16px; }

.toc-page {
  color: var(--text);
  background: var(--bg);
  font-family: var(--font-sans);
}
.toc-page > main {
  max-width: 1120px;
  margin-inline: auto;
  padding: 32px 20px 64px;
}
.page-heading { margin-block: 24px 32px; }
.page-heading h1,
h1.page-heading {
  color: var(--text);
  font-family: var(--font-serif);
  font-size: 26px;
  line-height: 1.25;
}
.page-heading h1 { margin: 0 0 16px; }
.book-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 24px;
  margin-block: 16px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.5;
  font-variant-numeric: tabular-nums;
}
.reading-status {
  margin-block: 16px 24px;
  padding: 12px 16px;
  border-inline-start: 3px solid var(--accent);
  background: var(--surface);
  color: var(--text);
  font-size: 14px;
  line-height: 1.8;
}
.toc-list {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.toc-list > li { min-width: 0; break-inside: avoid; }
.chapter-link {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
  height: 100%;
  min-height: 44px;
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  background: var(--surface);
  line-height: 1.5;
  text-decoration: none;
  overflow-wrap: anywhere;
}
.chapter-title-zh { font-size: 18px; font-weight: 600; }
.chapter-title-en {
  color: var(--muted);
  font-size: 14px;
  font-weight: 400;
}
.chapter-dateline { color: var(--muted); font-size: 14px; }
.chapter-status {
  margin-top: auto;
  padding-top: 8px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 600;
}
.chapter-link.is-read,
.toc-list > .is-read > .chapter-link { border-style: dashed; }
.chapter-link.is-current,
.chapter-link[aria-current="page"],
.toc-list > .is-current > .chapter-link {
  border-color: var(--accent);
  border-style: solid;
  border-inline-start-width: 4px;
}
.is-read .chapter-status:empty::after,
.chapter-status.is-read:empty::after { content: "✓ 已读"; }
.is-current .chapter-status:empty::after,
[aria-current="page"] .chapter-status:empty::after,
.chapter-status.is-current:empty::after { content: "正在阅读"; }
.toc-actions,
.footer-links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 24px;
  margin-top: 32px;
}
.footer-links a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  color: var(--accent);
  text-underline-offset: .25em;
  overflow-wrap: anywhere;
}
.chapter-link:focus-visible,
.reading-actions > a:focus-visible,
.toc-actions > a:focus-visible,
.contact-item a:focus-visible,
.footer-links a:focus-visible,
.back-to-top:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
}
@media (hover: hover) {
  .chapter-link:hover { border-color: var(--accent); }
  .chapter-link:hover .chapter-title-zh {
    text-decoration: underline;
    text-underline-offset: .25em;
  }
  .reading-actions > a:hover,
  .toc-actions > a:hover,
  .back-to-top:hover { border-color: var(--accent); }
}
@media (min-width: 768px) {
  .home-main { padding: 64px 40px; }
  .home-hero {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    column-gap: 24px;
  }
  .book-title { font-size: 56px; }
  .book-facts,
  .reading-actions { grid-column: 1 / -1; }
  .feature-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 24px; }
  .toc-page > main { padding: 48px 40px 64px; }
  .page-heading h1,
  h1.page-heading { font-size: 32px; }
  .toc-list { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 24px; }
}
@media (min-width: 1024px) {
  .toc-list { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
.toc-list--drawer { grid-template-columns: minmax(0, 1fr); gap: 8px; }
.toc-list--drawer .chapter-link { gap: 4px; padding: 12px 16px; }
.toc-list--drawer .chapter-title-zh { font-size: 16px; }
.toc-list--drawer .chapter-title-en,
.toc-list--drawer .chapter-dateline { font-size: 13px; }
.toc-list--drawer .chapter-status { padding-top: 4px; }
/* 阅读外壳；增强脚本在根元素添加 .js，浮层以 hidden 控制可见性。 */
.reader-page {
  min-height: 100vh;
  margin: 0;
  padding-top: 56px;
  padding-bottom: 48px;
  background: var(--bg);
  color: var(--text);
}
#topbar {
  position: fixed;
  z-index: 30;
  inset: 0 0 auto;
  box-sizing: border-box;
  height: 56px;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 40px;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  font: 15px/1.5 var(--font-sans);
  transition: transform .2s ease, opacity .2s ease, visibility .2s;
}
.reader-brand { flex: 0 0 auto; color: var(--accent); font-weight: 700; }
.reader-topbar__chapter {
  flex: 1 1 auto;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  color: var(--muted);
}
.reader-topbar__actions { display: flex; align-items: center; gap: 4px; }
#topbar a, #topbar button {
  display: inline-flex;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 8px;
}
.reader-control__short { display: none; }
html[data-ui="hidden"] #topbar {
  transform: translateY(-100%);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}
.reader-progress-track {
  position: fixed;
  z-index: 35;
  inset: 0 0 auto;
  height: 3px;
  background: var(--border);
  pointer-events: none;
}
#progress-bar {
  position: fixed;
  z-index: 36;
  inset: 0 auto auto 0;
  width: 0;
  max-width: 100%;
  height: 3px;
  background: var(--accent);
  pointer-events: none;
}
#bottombar {
  position: fixed;
  z-index: 30;
  inset: auto 0 0;
  box-sizing: border-box;
  height: 48px;
  display: none;
  align-items: center;
  justify-content: center;
  gap: 24px;
  border-top: 1px solid var(--border);
  background: var(--bg);
  font: 14px/1.5 var(--font-sans);
  transition: transform .2s ease, background-color .2s ease;
}
html.js #bottombar { display: flex; }
#bottombar button { min-height: 44px; min-width: 88px; }
#page-indicator {
  min-width: 8em;
  text-align: center;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
  transition: transform .2s ease;
}
html[data-ui="hidden"] #bottombar {
  transform: translateY(28px);
  border-color: transparent;
  background: transparent;
  pointer-events: none;
}
html[data-ui="hidden"] #bottombar button { visibility: hidden; }
html[data-ui="hidden"] #page-indicator {
  transform: translateY(-14px);
  background: var(--bg);
  font-size: 12px;
  line-height: 20px;
}
.chapter-heading {
  box-sizing: border-box;
  width: calc(100% - 80px);
  max-width: 38em;
  margin: 48px auto 32px;
  font-size: var(--reader-size);
}
.chapter-heading h1 {
  margin: 0 0 12px;
  font: 700 32px/1.25 var(--font-serif);
  text-wrap: balance;
}
.chapter-heading__en, .chapter-heading__dateline {
  margin: 8px 0 0;
  color: var(--muted);
  font: 15px/1.5 var(--font-sans);
}
html[data-lang-mode="en"] .chapter-heading [data-lang="zh"] { display: none; }
html[data-lang-mode="en"] .chapter-heading__en {
  color: var(--text);
  font-size: 24px;
}
html[data-lang-mode="zh"] .chapter-heading__en { color: var(--muted); }
#reader-main {
  position: relative;
  box-sizing: border-box;
  width: calc(100% - 80px);
  max-width: 38em;
  min-width: 0;
  margin: 0 auto;
  font-size: var(--reader-size);
}
#pane-zh, #pane-en {
  box-sizing: border-box;
  min-width: 0;
  min-height: 0;
  scroll-padding-block: 16px;
}
#pane-en { display: none; }
html[data-lang-mode="zh"] #pane-zh,
html[data-lang-mode="en"] #pane-en { display: block; }
html[data-lang-mode="zh"] #pane-en,
html[data-lang-mode="en"] #pane-zh { display: none; }
html[data-lang-mode="dual"][data-dual-layout="columns"] #reader-main {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 32px;
  max-width: calc(76em + 32px);
  height: calc(100vh - 56px - 48px);
  height: calc(100dvh - 56px - 48px);
}
html[data-lang-mode="dual"][data-dual-layout="columns"] #reader-main::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 50%;
  border-left: 1px solid var(--border);
  pointer-events: none;
}
html[data-lang-mode="dual"][data-dual-layout="columns"] #pane-en,
html[data-lang-mode="dual"][data-dual-layout="columns"] #pane-zh {
  display: block;
  grid-row: 1;
  height: 100%;
  overflow-y: auto;
  overflow-x: hidden;
  scrollbar-width: thin;
  scrollbar-color: var(--border) var(--bg);
}
html[data-lang-mode="dual"][data-dual-layout="columns"] #pane-en { grid-column: 1; }
html[data-lang-mode="dual"][data-dual-layout="columns"] #pane-zh { grid-column: 2; }
html[data-lang-mode="dual"][data-dual-layout="tabs"] #pane-zh,
html[data-lang-mode="dual"][data-dual-layout="tabs"] #pane-en { display: none; }
html[data-lang-mode="dual"][data-dual-layout="tabs"][data-active-pane="zh"] #pane-zh,
html[data-lang-mode="dual"][data-dual-layout="tabs"][data-active-pane="en"] #pane-en {
  display: block;
}
#lang-tabs {
  position: fixed;
  z-index: 25;
  inset: 56px 0 auto;
  box-sizing: border-box;
  height: 44px;
  display: none;
  justify-content: center;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  font: 14px/1.5 var(--font-sans);
}
html.js[data-lang-mode="dual"][data-dual-layout="tabs"] #lang-tabs { display: flex; }
html.js[data-lang-mode="dual"][data-dual-layout="tabs"] .reader-page {
  padding-top: 100px;
}
#lang-tabs button {
  flex: 0 1 180px;
  min-height: 44px;
  border: 0;
  border-bottom: 3px solid transparent;
  border-radius: 0;
  background: transparent;
  color: var(--muted);
}
html[data-active-pane="zh"] #lang-tabs [data-tab-lang="zh"],
html[data-active-pane="en"] #lang-tabs [data-tab-lang="en"] {
  border-bottom-color: var(--accent);
  color: var(--accent);
  font-weight: 700;
}
#chapter-nav {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  gap: 16px;
  box-sizing: border-box;
  width: calc(100% - 80px);
  max-width: 48rem;
  margin: 48px auto;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  font: 15px/1.5 var(--font-sans);
}
#chapter-nav a { display: flex; align-items: center; min-height: 44px; }
#nav-toc { justify-content: center; }
#nav-next { justify-content: flex-end; text-align: right; }
#drawer, #settings-panel {
  position: fixed;
  z-index: 60;
  inset: 0 0 0 auto;
  display: flex;
  flex-direction: column;
  box-sizing: border-box;
  width: 360px;
  max-width: calc(100% - 32px);
  max-height: 100vh;
  max-height: 100dvh;
  overflow-y: auto;
  overscroll-behavior: contain;
  border: 1px solid var(--border);
  border-radius: var(--radius) 0 0 var(--radius);
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow);
  font: 15px/1.5 var(--font-sans);
  transform: translateX(0);
  transition: transform .2s ease, opacity .2s ease;
}
#scrim {
  position: fixed;
  z-index: 50;
  inset: 0;
  background: var(--terminal-bg);
  opacity: .6;
  transition: opacity .2s ease;
}
#drawer[hidden], #settings-panel[hidden], #scrim[hidden] { display: none; }
#drawer[data-state="closing"], #settings-panel[data-state="closing"] {
  transform: translateX(100%);
  opacity: 0;
  pointer-events: none;
}
#scrim[data-state="closing"] { opacity: 0; pointer-events: none; }
.reader-dialog__header, .reader-dialog__footer { flex: 0 0 auto; padding: 16px 24px; }
.reader-dialog__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  border-bottom: 1px solid var(--border);
}
.reader-dialog__header h2 { margin: 0; font-size: 20px; line-height: 1.25; }
.reader-dialog__header button { min-width: 44px; min-height: 44px; }
.reader-dialog__body { flex: 1 1 auto; min-height: 0; overflow-y: auto; padding: 24px; }
.reader-dialog__footer { border-top: 1px solid var(--border); color: var(--muted); }
#drawer-toc { margin: 0; padding: 16px 24px 24px 48px; }
#drawer-toc a { display: block; min-height: 44px; padding: 8px; box-sizing: border-box; }
#drawer-toc [aria-current="page"] { color: var(--accent); font-weight: 700; }
.setting-group { min-width: 0; margin: 0 0 24px; padding: 0; border: 0; }
.setting-group legend, .setting-group h3 {
  margin: 0 0 12px;
  padding: 0;
  font-size: 15px;
  font-weight: 700;
}
.setting-options { display: flex; flex-wrap: wrap; gap: 8px; }
.setting-options button {
  min-width: 44px;
  min-height: 44px;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--figure-radius);
  background: var(--bg);
  color: var(--text);
  font: inherit;
}
.setting-options [aria-pressed="true"] {
  border-color: var(--accent);
  outline: 2px solid var(--accent);
  outline-offset: -3px;
  color: var(--accent);
  font-weight: 700;
}
.settings-note, .setting-help, .reader-shortcuts {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.7;
}
.reader-shortcuts { display: flex; flex-wrap: wrap; gap: 8px 16px; }
.reader-notice {
  display: block;
  margin: 16px auto;
  padding: 12px 16px;
  max-width: 38rem;
  border-left: 3px solid var(--accent);
  background: var(--surface);
  font: 14px/1.7 var(--font-sans);
}
@media (max-width: 767px) {
  #topbar { gap: 8px; padding-inline: 20px; font-size: 14px; }
  .reader-topbar__actions { gap: 0; }
  .reader-control__label { display: none; }
  .reader-control__short { display: inline; }
  .chapter-heading { margin-block: 32px 24px; }
  .chapter-heading, #reader-main, #chapter-nav { width: calc(100% - 40px); }
  .chapter-heading h1 { font-size: 26px; }
  #bottombar { gap: 8px; }
  #chapter-nav { gap: 8px; font-size: 14px; }
  #drawer, #settings-panel {
    inset: auto 0 0;
    width: 100%;
    max-width: 100%;
    max-height: 85vh;
    max-height: 85dvh;
    padding-bottom: env(safe-area-inset-bottom, 0px);
    border-radius: var(--radius) var(--radius) 0 0;
  }
  #drawer[data-state="closing"], #settings-panel[data-state="closing"] {
    transform: translateY(100%);
  }
}
@media (prefers-reduced-motion: reduce) {
  #topbar, #bottombar, #page-indicator, #drawer, #settings-panel, #scrim {
    transition: none;
  }
}
.chapter-content {
  min-width: 0;
  max-width: 100%;
  color: var(--text);
  font-family: var(--reader-font);
  font-size: var(--reader-size);
  line-height: var(--reader-leading);
  line-break: strict;
  word-break: normal;
  overflow-wrap: break-word;
  text-spacing-trim: trim-start;
}
.chapter-content .chapter-title {
  margin: 0 0 24px;
  font-size: 1.6em;
  font-weight: 600;
  line-height: 1.25;
  text-align: center;
  text-indent: 0;
  break-after: avoid;
}
.chapter-content p {
  margin: 0;
  text-indent: 2em;
  text-align: justify;
  line-break: strict;
  word-break: normal;
  overflow-wrap: break-word;
  text-spacing-trim: trim-start;
  line-height: var(--reader-leading);
  orphans: 2;
  widows: 2;
}
.chapter-content .dateline,
.chapter-content .scene-break {
  margin: 24px 0;
  color: var(--muted);
  text-align: center;
  text-indent: 0;
}
.chapter-content .dateline {
  margin-top: 0;
  font-size: 0.85em;
}
.chapter-content hr.rule {
  width: 32%;
  margin: 32px auto;
  border: 0;
  border-top: 1px solid var(--border);
}
.chapter-content blockquote {
  margin: 24px 0;
  padding-inline: 20px;
  border-inline-start: 3px solid var(--border);
}
.chapter-content .dialog { padding-block: 4px; }
.chapter-content .dialog.railed {
  border-inline-start: 3px solid currentColor;
  padding-inline-start: 16px;
}
.chapter-content ul,
.chapter-content ol {
  margin-block: 16px;
  padding-inline-start: 2em;
}
.chapter-content li {
  padding-inline-start: 4px;
  text-indent: 0;
}
.chapter-content li + li { margin-top: 4px; }
.chapter-content sup,
.chapter-content sub {
  position: relative;
  font-size: 0.7em;
  line-height: 0;
  vertical-align: baseline;
}
.chapter-content sup { top: -0.5em; }
.chapter-content sub { bottom: -0.2em; }
.chapter-content code {
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.9em;
  overflow-wrap: anywhere;
}
.chapter-content b,
.chapter-content strong { font-weight: 700; }
.chapter-content em { font-style: italic; }
.chapter-content figure.fig {
  box-sizing: border-box;
  max-width: 100%;
  margin: 24px auto;
  padding: 8px;
  overflow: auto;
  border-radius: var(--figure-radius);
  background: var(--terminal-bg);
  color: var(--terminal-text);
  text-align: center;
  text-indent: 0;
  break-inside: avoid;
}
.chapter-content figure.fig img {
  display: block;
  max-width: 100%;
  height: auto;
  margin-inline: auto;
  object-fit: contain;
}
.chapter-content figure.fig figcaption {
  padding: 8px 4px 0;
  font: 0.75em/1.5 var(--font-sans);
  text-align: center;
}
.device-view {
  box-sizing: border-box;
  min-width: 0;
  max-width: 100%;
  margin: 24px auto;
  padding: 16px;
  overflow-x: auto;
  border-radius: var(--radius);
  background: var(--terminal-bg);
  color: var(--terminal-text);
  color-scheme: dark;
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.85em;
  line-height: 1.7;
  text-align: start;
  text-indent: 0;
  overflow-wrap: anywhere;
  overscroll-behavior: contain;
  scrollbar-width: thin;
  scrollbar-color: var(--terminal-text) var(--terminal-bg);
  break-inside: avoid;
}
.wide-device-view { width: 100%; }
.device-view-left { margin-inline: 0 auto; text-align: start; }
.chapter-content .device-view p {
  text-indent: 0;
  text-align: start;
  line-height: inherit;
}
.device-view table {
  width: 100%;
  border-collapse: collapse;
  font: inherit;
  text-align: start;
}
.device-view th,
.device-view td {
  padding: 8px 12px;
  border: 1px solid var(--terminal-text);
  text-align: start;
  vertical-align: top;
  overflow-wrap: anywhere;
}
.device-view thead {
  background: var(--terminal-text);
  color: var(--terminal-bg);
}
.device-view input[type="range"] {
  box-sizing: border-box;
  display: block;
  width: 100%;
  min-width: 0;
  min-height: 44px;
  margin: 4px 0;
  accent-color: var(--terminal-text);
}
.device-view input[type="range"]:disabled { opacity: 1; }
.device-view button {
  min-height: 44px;
  max-width: 100%;
  padding: 8px 12px;
  border: 1px solid var(--terminal-text);
  border-radius: var(--figure-radius);
  background: var(--terminal-bg);
  color: var(--terminal-text);
  font: inherit;
  white-space: normal;
}
.device-view button:disabled,
.device-view button[aria-disabled="true"] {
  opacity: 1;
  cursor: default;
  box-shadow: none;
  transform: none;
}
.device-view [style*="display"][style*="flex"] {
  box-sizing: border-box;
  min-width: 0;
  max-width: 100%;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  padding-block: 8px;
}
.device-view [style*="display"][style*="flex"] > span {
  flex: 0 1 auto;
  align-self: center;
  max-width: 100%;
  white-space: nowrap;
  line-height: 1.5;
}
.dz-script {
  font-family: Georgia, "Palatino Linotype", "Songti SC", cursive, serif;
  font-style: italic;
  letter-spacing: 0.04em;
}
.dz-card {
  box-sizing: border-box;
  max-width: 100%;
  margin: 24px 0;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  overflow-wrap: anywhere;
  break-inside: avoid;
}

/* 视口高度由阅读布局确定；flow 的一列正好等于视口宽度。 */
html[data-page-mode="paged"] .reader-viewport {
  box-sizing: border-box;
  width: 100%;
  height: 100%;
  min-width: 0;
  min-height: 0;
  overflow: hidden;
  scrollbar-width: none;
}
html[data-page-mode="paged"] .reader-flow {
  box-sizing: border-box;
  width: 100%;
  height: 100%;
  min-width: 0;
  margin: 0;
  column-count: 1;
  column-width: auto;
  column-gap: 32px;
  column-fill: auto;
  overflow: visible;
  transform-origin: left top;
  transition: none;
}
html[data-page-mode="paged"] .reader-flow > .chapter-content {
  height: 100%;
}
html[data-page-mode="paged"] .reader-flow figure.fig,
html[data-page-mode="paged"] .reader-flow .device-view,
html[data-page-mode="paged"] .reader-flow .dz-card {
  max-height: 100%;
  margin-block: 0;
  overflow: auto;
  break-inside: avoid;
}
html[data-page-mode="paged"] .reader-flow figure.fig img {
  max-height: 100%;
  object-fit: contain;
}
html[data-page-mode="paged"] .reader-viewport::-webkit-scrollbar {
  display: none;
}
/* 内部终端仍保留滚动提示，不隐藏其滚动条。 */
@media (max-width: 768px) {
  .chapter-content .chapter-title { font-size: 1.45em; }
  .chapter-content blockquote { padding-inline: 12px; }
  .chapter-content figure.fig { width: 100%; padding: 4px; }
  .chapter-content figure.fig img { width: 100%; }
  .device-view { padding: 12px; }
  .device-view th, .device-view td { padding: 8px; }
  html:not([data-js]) .chapter-content {
    font-size: 18px;
    line-height: 1.8;
  }
  html:not([data-js]) .chapter-content p { line-height: 1.8; }
}

html:not([data-js]) body.reader-page { overflow: auto; height: auto; }
html:not([data-js]) #reader-main {
  display: block;
  height: auto;
  max-height: none;
  overflow: visible;
}
html:not([data-js]) #pane-zh {
  display: block;
  width: 100%;
  max-width: 38em;
  height: auto;
  margin-inline: auto;
  overflow: visible;
}
html:not([data-js]) #pane-en,
html:not([data-js]) #lang-tabs,
html:not([data-js]) #bottombar,
html:not([data-js]) #drawer,
html:not([data-js]) #settings-panel,
html:not([data-js]) #scrim { display: none; }
html:not([data-js]) #reader-main .reader-viewport,
html:not([data-js]) #reader-main .reader-flow,
html:not([data-js]) #reader-main .chapter-content {
  height: auto;
  max-height: none;
  overflow: visible;
  columns: auto;
  transform: none;
}
html:not([data-js]) #reader-main figure.fig,
html:not([data-js]) #reader-main .device-view,
html:not([data-js]) #reader-main .dz-card { max-height: none; }

@media print {
  html, html body { height: auto; overflow: visible; background: none; color: black; }
  #topbar, #bottombar, #progress-bar, #lang-tabs, #chapter-nav,
  #drawer, #settings-panel, #scrim, .skip-link,
  body.reader-page button, body.reader-page input,
  body.reader-page select, body.reader-page textarea { display: none !important; }
  html #reader-main {
    display: flex;
    flex-direction: column;
    position: static;
    width: auto;
    height: auto;
    margin: 0;
    padding: 0;
    overflow: visible;
  }
  html #reader-main [data-lang],
  html #reader-main .reader-viewport,
  html #reader-main .reader-flow,
  html #reader-main .chapter-content {
    position: static;
    width: auto;
    max-width: none;
    height: auto !important;
    max-height: none;
    margin: 0;
    padding: 0;
    overflow: visible;
    columns: auto;
    transform: none !important;
    contain: none;
    background: none;
    color: black;
  }
  html #reader-main #pane-zh { display: block; order: 2; }
  html #reader-main #pane-en { display: none; order: 1; }
  html[data-js][data-lang-mode="en"] #reader-main #pane-zh { display: none; }
  html[data-js][data-lang-mode="en"] #reader-main #pane-en,
  html[data-js][data-lang-mode="dual"] #reader-main #pane-en { display: block; }
  html[data-js][data-lang-mode="dual"] #reader-main #pane-zh { display: block; }
  html #reader-main figure.fig, html #reader-main .device-view,
  html #reader-main .dz-card {
    max-height: none;
    overflow: visible;
    background: none;
    color: black;
    box-shadow: none;
    break-inside: auto;
  }
  html #reader-main figure.fig img { max-height: none; }
  .device-view thead { background: none; color: black; }
  .device-view th, .device-view td { border-color: currentColor; }
  .chapter-content .chapter-title { break-after: avoid; }
}